ABCA1/ABCB1 Ratio Determines Chemo- and Immune-Sensitivity in Human Osteosarcoma.

Dimas Carolina Belisario,Virginia Campani,Massimo Serra,Claudia Maria Hattinger,Martina Godel,Muhlis Akman,Lorena Scotti,Joanna Kopecka,Giuseppe De Rosa,Chiara Riganti,Massimo Donadelli,Maria Pia Patrizio

doi:10.3390/cells9030647

Abstract

The ATP Binding Cassette transporter B1 (ABCB1) induces chemoresistance in osteosarcoma, because it effluxes doxorubicin, reducing the intracellular accumulation, toxicity, and immunogenic cell death induced by the drug. The ATP Binding Cassette transporter A1 (ABCA1) effluxes isopentenyl pyrophosphate (IPP), a strong activator of anti-tumor Vγ9Vδ2 T-cells. Recruiting this population may represent an alternative strategy to rescue doxorubicin efficacy in ABCB1-expressing osteosarcoma. In this work, we analyzed how ABCA1 and ABCB1 are regulated in osteosarcoma, and if increasing the ABCA1-dependent activation of Vγ9Vδ2 T-cells could be an effective strategy against ABCB1-expressing osteosarcoma. We used 2D-cultured doxorubicin-sensitive human U-2OS and Saos-2 cells, their doxorubicin-resistant sublines (U-2OS/DX580 and Saos-2/DX580), and 3D cultures of U-2OS and Saos-2 cells. DX580-sublines and 3D cultures had higher levels of ABCB1 and higher resistance to doxorubicin than parental cells. Surprisingly, they had reduced ABCA1 levels, IPP efflux, and Vγ9Vδ2 T-cell-induced killing. In these chemo-immune-resistant cells, the Ras/Akt/mTOR axis inhibits the ABCA1-transcription induced by Liver X Receptor α (LXRα); Ras/ERK1/2/HIF-1α axis up-regulates ABCB1. Targeting the farnesylation of Ras with self-assembling nanoparticles encapsulating zoledronic acid (NZ) simultaneously inhibited both axes. In humanized mice, NZ reduced the growth of chemo-immune-resistant osteosarcomas, increased intratumor necro-apoptosis, and ABCA1/ABCB1 ratio and Vγ9Vδ2 T-cell infiltration. We suggest that the ABCB1highABCA1low phenotype is indicative of chemo-immune-resistance. We propose aminobisphosphonates as new chemo-immune-sensitizing tools against drug-resistant osteosarcomas.

Highlights

The ATP Binding Cassette transporter B1 (ABCB1; P-glycoprotein, Pgp) determines the resistance to a broad spectrum of chemotherapeutic drugs and targeted therapies [1]
We found that ABCB1 and ATP Binding Cassette transporter A1 (ABCA1) are inversely expressed in osteosarcoma cells
We first compared the expression of ABCB1 and ABCA1 in doxorubicin-sensitive U-2OS cells, in the resistant counterpart U-2OS/DX580, and in 3D cultures of

Summary

Introduction

The ATP Binding Cassette transporter B1 (ABCB1; P-glycoprotein, Pgp) determines the resistance to a broad spectrum of chemotherapeutic drugs and targeted therapies [1]. ABCB1 effluxes doxorubicin [1], which, together with cisplatin and methotrexate, is the first-line treatment in patients affected by this tumor [5]. The active efflux of doxorubicin by ABCB1 is the main mechanism of resistance to doxorubicin in osteosarcoma [2,3,4], limiting the drug’s intracellular accumulation and cytotoxicity. Doxorubicin kills cancer cells via direct mechanisms, i.e., by inhibiting topoisomerase II, increasing reactive oxygen and nitrogen species, perturbing mitochondria functions [6], and indirect mechanisms, i.e., by increasing the ability of the host immune system to eradicate the target cells, producing an immunogenic cell death (ICD) [7]. Doxorubicin elicits the translocation of calreticulin from the endoplasmic reticulum to the plasma membrane

Results

Discussion

Conclusion